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Benazza R, Letissier L, Papadakos G, Thom J, Diemer H, Cotton G, Cianférani S, Hernandez-Alba O. Development of Top-Down Mass Spectrometry Strategies in the Chromatographic Time Scale (LC-TD-MS) for the Extended Characterization of an Anti-EGFR Single-Domain Antibody-Drug Conjugate in Both Reduced and Nonreduced Forms. Anal Chem 2025; 97:2639-2647. [PMID: 39889214 DOI: 10.1021/acs.analchem.4c03323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2025]
Abstract
Even though mAbs have attracted the biggest interest in the development of therapeutic proteins, next-generation therapeutics such as single-domain antibodies (sdAb) are propelling increasing attention as new alternatives with appealing applications in different clinical areas. These constructs are small therapeutic proteins formed by a variable domain of the heavy chain of an antibody with multiple therapeutic and production benefits compared with their mAb counterparts. These proteins can be subjected to different bioconjugation processes to form single-domain antibody-drug conjugates (sdADCs) and hence increase their therapeutic potency, and akin to other therapeutic proteins, nanobodies and related products require dedicated analytical strategies to fully characterize their primary structure prior to their release to the market. In this study, we report for the first time the extensive sequence characterization of a conjugated anti-EGFR 14 kDa sdADC by using state-of-the-art top-down mass spectrometry strategies in combination with liquid chromatography (LC-TD-MS). Mass analysis revealed a highly homogeneous sample with one conjugated molecule. Subsequently, the reduced sdADC was submitted to different fragmentation techniques, namely, higher-energy collisional dissociation, electron-transfer dissociation, and electron-transfer higher-energy collision dissociation, allowing to unambiguously assess the conjugation site with 24 diagnostic fragment ions and 85% of global sequence coverage. The sequence coverage of the nonreduced protein was significantly lower (around 16%); however, the analysis of the fragmentation spectra corroborated the presence of the intramolecular disulfide bridge along with the localization of the conjugation site. Altogether, our results pinpoint the difficulties and challenges associated with the fragmentation of sdAb-derived formats in the LC time scale due to their remarkable stability as a consequence of the intramolecular disulfide bridge. However, the use of complementary activation techniques along with the identification of specific ion fragments allows an improved sequence coverage, the characterization of the intramolecular disulfide bond, and the unambiguous localization of the conjugation site.
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Affiliation(s)
- Rania Benazza
- Laboratoire de Spectrométrie de Masse BioOrganique, IPHC UMR 7178, CNRS, Université de Strasbourg, 67087 Strasbourg, France
- Infrastructure Nationale de Protéomique ProFI-FR2048, 67087 Strasbourg, France
| | - Léa Letissier
- Laboratoire de Spectrométrie de Masse BioOrganique, IPHC UMR 7178, CNRS, Université de Strasbourg, 67087 Strasbourg, France
- Infrastructure Nationale de Protéomique ProFI-FR2048, 67087 Strasbourg, France
| | - Greg Papadakos
- Edinburgh Technopole, Almac Discovery, Milton Bridge, Penicuik, Scotland EH26 0BE, United Kingdom
| | - Jen Thom
- Edinburgh Technopole, Almac Discovery, Milton Bridge, Penicuik, Scotland EH26 0BE, United Kingdom
| | - Helene Diemer
- Laboratoire de Spectrométrie de Masse BioOrganique, IPHC UMR 7178, CNRS, Université de Strasbourg, 67087 Strasbourg, France
- Infrastructure Nationale de Protéomique ProFI-FR2048, 67087 Strasbourg, France
| | - Graham Cotton
- Edinburgh Technopole, Almac Discovery, Milton Bridge, Penicuik, Scotland EH26 0BE, United Kingdom
| | - Sarah Cianférani
- Laboratoire de Spectrométrie de Masse BioOrganique, IPHC UMR 7178, CNRS, Université de Strasbourg, 67087 Strasbourg, France
- Infrastructure Nationale de Protéomique ProFI-FR2048, 67087 Strasbourg, France
| | - Oscar Hernandez-Alba
- Laboratoire de Spectrométrie de Masse BioOrganique, IPHC UMR 7178, CNRS, Université de Strasbourg, 67087 Strasbourg, France
- Infrastructure Nationale de Protéomique ProFI-FR2048, 67087 Strasbourg, France
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Nybo T, Gamon LF, Fuentes-Lemus E, Otzen DE, Davies MJ, Hägglund P. Dimethyl labeling of N-terminal amines allows unambiguous identification of protein crosslinks. Free Radic Biol Med 2025; 227:629-637. [PMID: 39643131 DOI: 10.1016/j.freeradbiomed.2024.12.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2024] [Revised: 11/28/2024] [Accepted: 12/02/2024] [Indexed: 12/09/2024]
Abstract
Protein crosslinks induced through either deliberate enzymatic oxidation or reactive oxidants (oxidative eustress/distress), are associated with multiple human pathologies including atherosclerosis, Alzheimer's and Parkinson's diseases. In many cases, the nature of the crosslinks, their position(s) either within (intramolecular) or between (intermolecular) polypeptide chains, and concentrations are unclear. Although limited data are available from specific antibodies, detailed characterization of protein crosslinks is often performed by mass spectrometric analysis of peptides from proteolytic digestion. Such analyses are challenging due to the low concentration of these species, and the complexity of their fragment ion spectra when compared to non-crosslinked species. We hypothesized that highly efficient and specific chemical amine labeling of the two N-termini in crosslinked peptides (compared to the single N-terminus of linear peptides), using "light" and "heavy" isotope-labelled reagents would facilitate identification, validation and quantification of crosslinks. This method was compared to a previous enzyme-catalyzed 18O C-terminal carboxylate labeling approach. N-terminal amine dimethyl labeling is shown to have major advantages over the 18O-approach including high labeling yields (92-100 %) and well-defined mass spectrometric isotope distribution patterns. This approach has allowed identification of novel dityrosine crosslinks between pair of tyrosine (Tyr, Y) residues in photo-oxidized β-casein (Y195-Y195, Y195-Y208, Y208-Y208), and α-synuclein exposed to nitrosative stress (Y39-Y39, Y39-Y125, Y39-Y133, Y133-Y136). This approach is also applicable to disulfide bond mapping, with 15 of 17 disulfides in serum albumin readily detected. These data indicate that dimethyl labeling is a highly versatile and efficient approach for the site-specific identification of oxidation- and nitration-induced crosslinks in proteins.
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Affiliation(s)
- Tina Nybo
- Dept. of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Luke F Gamon
- Dept. of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | | | - Daniel E Otzen
- Interdisciplinary Nanoscience Center (iNANO) Aarhus University, Gustav Wieds Vej 14, 8000, Aarhus C, Denmark; Department of Molecular Biology and Genetics, Universitetsbyen 81, 8000, Aarhus C, Denmark
| | - Michael J Davies
- Dept. of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark.
| | - Per Hägglund
- Dept. of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark.
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Wei B, Zenaidee MA, Lantz C, Williams BJ, Totten S, Ogorzalek Loo RR, Loo JA. Top-down mass spectrometry and assigning internal fragments for determining disulfide bond positions in proteins. Analyst 2022; 148:26-37. [PMID: 36399030 PMCID: PMC9772244 DOI: 10.1039/d2an01517j] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Disulfide bonds in proteins have a substantial impact on protein structure, stability, and biological activity. Localizing disulfide bonds is critical for understanding protein folding and higher-order structure. Conventional top-down mass spectrometry (TD-MS), where only terminal fragments are assigned for disulfide-intact proteins, can access disulfide information, but suffers from low fragmentation efficiency, thereby limiting sequence coverage. Here, we show that assigning internal fragments generated from TD-MS enhances the sequence coverage of disulfide-intact proteins by 20-60% by returning information from the interior of the protein sequence, which cannot be obtained by terminal fragments alone. The inclusion of internal fragments can extend the sequence information of disulfide-intact proteins to near complete sequence coverage. Importantly, the enhanced sequence information that arise from the assignment of internal fragments can be used to determine the relative position of disulfide bonds and the exact disulfide connectivity between cysteines. The data presented here demonstrates the benefits of incorporating internal fragment analysis into the TD-MS workflow for analyzing disulfide-intact proteins, which would be valuable for characterizing biotherapeutic proteins such as monoclonal antibodies and antibody-drug conjugates.
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Affiliation(s)
- Benqian Wei
- Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, CA, USA.
| | - Muhammad A Zenaidee
- Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, CA, USA.
- Australian Proteome Analysis Facility, Macquarie University, Macquarie Park, NSW, Australia
| | - Carter Lantz
- Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, CA, USA.
| | | | | | - Rachel R Ogorzalek Loo
- Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, CA, USA.
| | - Joseph A Loo
- Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, CA, USA.
- Department of Biological Chemistry, University of California Los Angeles, Los Angeles, CA, USA
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Watts E, Thyer R, Ellington AD, Brodbelt JS. Integrated Top-Down and Bottom-Up Mass Spectrometry for Characterization of Diselenide Bridging Patterns of Synthetic Selenoproteins. Anal Chem 2022; 94:11175-11184. [PMID: 35930618 DOI: 10.1021/acs.analchem.2c01433] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
With the rapid acceleration in the design and development of new biotherapeutics, ensuring consistent quality and understanding degradation pathways remain paramount, requiring an array of analytical methods including mass spectrometry. The incorporation of non-canonical amino acids, such as for synthetic selenoproteins, creates additional challenges. A comprehensive strategy to characterize selenoproteins should serve dual purposes of providing sequence confirmation and mapping of selenocysteine bridge locations and the identification of unanticipated side products. In the present study, a combined approach exploiting the benefits of both top-down and bottom-up mass spectrometry was developed. Both electron-transfer/higher-energy collision dissociation and 213 nm ultraviolet photodissociation were utilized to provide complementary information, allowing high quality characterization, localization of diselenide bridges for complex proteins, and the identification of previously unreported selenoprotein dimers.
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Affiliation(s)
- Eleanor Watts
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
| | - Ross Thyer
- Chemical and Biomolecular Engineering, Rice University, Houston, Texas 77005, United States
| | - Andrew D Ellington
- Center for Systems and Synthetic Biology, University of Texas at Austin, Austin, Texas 78712, United States
| | - Jennifer S Brodbelt
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
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